ASME B16.1-2020 PDF
This Standard for Classes 25, 125, and 250 Cast Iron Pipe Flanges and Flanged Fittings. It includes
(a) pressure-temperature ratings,
(b) sizes and method of designating openings of reducing fittings,
(c) marking,
(d) materials,
(e) dimensions and tolerances,
(f) bolting and gaskets
(g) pressure testing.